Nanodiagnostics involve the use of nanotechnology in biomedical diagnostics. Various aspects of the relationship between biomedical nanotechnology and diagnostics are discussed below.
Lab on chip (LOC) is device that integrates laboratory functions on nano chip. Image Credit: Science photo / Shutterstock
Protein nanobiochip (NBC) is a device that combines nanotechnology-based biochips and microarrays. Due to the challenges of detecting protein on microarrays, protein nanobiochips are beginning to be widely used. They can be used at point-of-care and are generated by spotting cDNA on glass slides which are then translated to target proteins. The NBC use a 3D ‘nanonet’ which is a component of ‘microsponge’ which consists of a polymer membrane. The advantages of this method include that it can be created easily and the results can be obtained within minutes, making them available at point-of-care.
Cytogenetics is the technique used to visualise and measure the chromosome structure, and it has also been used to identify chromosomal abnormalities. It employs fluorescence in situ hybridization (FISH), where a fluorescent probe binds to a complementary sequence or a probe on the chromosome, helping to visualise it. However, the florescent microscopy has its limits of resolution. Recently, atomic force microscopy (AFM) and quantum dots (QD) are being used in FISH to visualise G-bands and other regions of chromosomes. QD have many advantages over conventional fluorescent probes, including a broad absorption spectrum, narrow emission spectra, and photostability. These properties make QD a stable and sensitive marker to visualise chromosomes which can also be used for longer durations of florescence imaging. Differently colored QD’s can also be excited simultaneously to image different regions of chromosomes together without getting any artifacts.
Nanoscale Identification of Single-Cell or Molecule
Proteomics have been in use for some time to detect changes in proteins and protein modification. However, nanoproteomics is enabling the detection of single molecule of protein. Using this method, cancer cells can be separated from the closely resembling non-cancer cells. The biobarcode assay is used to help detect trace amounts of proteins, which is not possible using conventional methods. This procedure can also be used to characterize biomarkers.
Nanoparticles to Discover Biomarkers
Nanotechnology can be used to detect new biomarkers, which can in the future replace conventional methods. Nanoparticles have a large surface area and specific physicochemical traits which help in the process of identifying biomarkers. The architecture and shape of biomarkers can also be tweaked to bind and sequester biomarkers which are then subsequently further characterised. To quickly detect biomarkers, the method employed is the use of polymer-coated nanoparticles.
Nanodiagnostics to Manage Cancer
One of the advanced techniques of detecting cancer involves combining QDs coated with paramagnetic liquid and silica nanoparticle to generate an MRI probe. This probe is being used to detect molecules involved in cancer. For example, polysialic acid, a tumor biomarker, is attached to its antibody, and this nanoparticle complex is taken up by cancer cells. Subsequently, it is imaged using florescence microscopy.
Similar methods have also been used to detect prostate cancer. In this case, anti-epidermal growth factor receptor was conjugate to gold nanoparticles which then bind to cancer cells with a much greater affinity. These particles can then be imaged and thus used to diagnose and detect cancer cells in the prostate.
Nanodiagnostics in Infectious Diseases
One of critical aspects to managing infectious diseases is the rapid detection of pathogens in patients. However, the conventional methods to detect pathogens are time-consuming and do not have high degree of sensitivity. Nanoparticle approaches have been recently used to detect and quantify pathogens in the sample. Using QDs as nanoprobes, single molecules can be imaged. In this this method, target sequences are hybridized with nanoprobes which are then used to detect pathogens using different viral DNA or RNA sequences. This technique provides fast, inexpensive and reproducible method to detect viruses in patients.